US1185510A - Telephone system. - Google Patents

Description

A. E. KEITH. TELEPHONE SYSTEM.

APPLICATION FILED JUNE 28,1911.

,W/T/VESSES TTOR/s/Eys,

Y A. E. KEITH. y TELEPHONE SYSTEM.

APPLICATION vFILED JUNEZB. 1911.

Patented May 30,1916.

6 SHEETS-SHEET 2.

TTOR/VENS,

A. E. KEITH.

TELEPHONE SYSTEM.

. APPLICATION FILED IuIIE 28. `I9II.

1,185,510. f I Patented May 30, 1916.

6 SHEETS-SHEET 3.

, 'MTA/55555 I I/I/E/ym/a cava. may. I gdwIymMc TTQRNEXS A. E. KEITH.

TELEPHONE SYSTEM. V APPLICATION FILED JUNE 28. 19H` 1,185,510. Patented Mayso, 1916.

6 SHEETS-SHEET 4 TMm/55555 @VENTUR- ,I/-.ESWM Mm@ 95..x4

A. E. KEI-TH. TELEPHONE SYSTEM. APPLICATION FILED IUNE 28. 19H.v

y l NVE/V701?.-

wg@ *MMA TTONEY,

A. KEITH. TELEPHONE SYSTEM.

APPLICATION FILED JUNE 28, 191i.

Patented May 30, 1916 6 SHEETS-SHEET 6.

INN I TZTOR/VEY@ ALEXANDER E. KEITH, OF HINSDALE, ILLINOIS, AFSSIGNOR TO yAU'IJOMA'II ELECTRIC COMPANY, 0F CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented May 30, 1,916.

Application filed June as, i911. v serial No. 635,697.

and more particularly to that type of system known as the line switch system that is, one in which line switches are employed which are individual to the subscribers lines for the-purpose of selecting an idle trunk, which trunk may extend to a tirst selector or the like.

Among the objects'of my invention are to provide an improved construction for the line switch, and to provide a line switch in which the operating magnet is movable with the operating plunger in the selecting operation of the switch.

A further 'object is to provide an irnproved and simplified construction of'master switch, which master switch controls a groupv of line switches, and to provide a master switch which has a continuous selecting motion and a continuous return motion, as distinguished from a step-by-step motion.

These and other objects of my invention will be more clearly understood by reference tothe accompanying drawings, in"

which similar reference characters refer to similar parts, and in which- Figure 1 is atop view of my improved combined line and cut-off relay. a side view of the same. Fig. 3 isa section taken' on the line 3 3 of Fig. 1. Fig. 4 is a view of one of the relays in its operated position. Fig. 5 is a side view of one oit the subscribers individual switches. Fig. 5 is a top view of the solenoid 47 in Fig. 5. Fig. 6 is a view showing two of the switches, showing how they are mounted relatively to each other, one of them being shown in section. Fig. 7 is a side view of the master switch. Fig. 8 is a top view of the same. Figs. 9 and 10 taken together show a com plete connection between the calling and called substations in a system embodying the principles of my invention.

The construction of. the combined line and cut-oit relays shown in Figs. 1 2, 3 and 4 is as follows: In these figures, 3 and 4 vare Fig. 2 is 'two lmetal tubes oined by atiat strip 2. The strip 2 and the tubes 3 and 4 are formed out of a single piece of metal which'is punched I out of a flat sheet and formed into thel proper shape. The vtubes form casings for the -relay wlndings 5 and 6. The winding 6 has a statlonary core 7 and the pivoted armature 8. The winding 5 is provided with a movable plunger, to the end of which there is secured a i'lat disk or armature 21.

As shown, each relay controls two sets of are mounted on the strip v2 between the windings 5 and 6, and are held in place between suitable insulating bushings by the and two movable springs 12 and 13. When the winding is energized, the armature 8 is attracted, and, through the medium of the arm 14, forces the springs 12 and" 13 into contact with the springs 10 and 11. The relay 5 controls aset of Vnormally closed springs and a set of normally open springs. Journaled between the arms 15 and 16 there is a small lever '17 provided. with thebushings 18 and 19. The lever 17 is connected with the plunger ofthe relay 5 by a short link 22. Vhenthe winding is denergized, the plunger is held in its retracted position, as shown in Figs. 2 and 3, by the spring 23. In this position, the bushing 18 on the lever 17 forces the springs 24 and 25 into contact with the springs 26 and' 27.l When the winding is energized, the plunger is forced to theright and the lever-17 is rocked into the position shown in Fig. 4. In this position, the springs 24 and 25 are permitted to separate from the springs 26 and 27, and the springs 29, 30, 31 and 32 are forced into contact with the springs 33, 34, 35 and 36, respectively.' The contact springs of the relays are provided with suitable terminals 33a (Fig. 1) by means of which electrical connections may be made therewith. It will be understood, of course, that although I have shown and described one particular spring combination for these relays, any suitable arrangement of springs may be used without departing from the spirit of the invention-that is, the numberof springs controlled by either relay may be .eitherinsprings placed side by side. These springs4 I of these relays are lient outward..y ith they are forced into contact with 'the tionary springs, there is a 'tendency straighten out the movable spri s, t by lengthening theni slightly. a slight rubbing 'motion between inovable springs and the stationary spinge. This serves to keep the Contact surfaces bright and cleana thereby insuring a goed l@ contact-without the use of platinum 4ccaiitact points.

The subscribers individual shown in Figs. 5 and 6 is, in general prir-.ciples5 Very similar to that disclosed in British Patu ent No. 26,301 of i906, and in the Americanlclephoue Jou/mal of New York9 N. Y., of J une 6, i908. Each switch is provided with Va number of sets of contact springs similar to the set 3'?, 38, 39, 4()j 4l., 43 and 44. rlhese sets oi' springs arranged on the arc of a circle and clamped between the plates 45 and 46 and are separated from each other by suitable insulating bushings. Pivoted between the plates 45 and 46 there is a solenoid 47. To the lower end the movable core of the solenoid there is attached a plunger 48 the point of which projects downward between the Contact springs of the switch. To the lower end of the plun- 3@ ger 48 there are attached two small bushings 49 and 50. l-Nhen the plunger is retracteds these bushings are high enough to just pass over the top or" the Contact springs as the solenoid is moved about its pivots. When the solenoid is energized7 its plunger is drawn downward, forcing the bushings 49 and 50 against the springs 40 and 4l of whichever groupbiZ springs the plunger is then opposite, and as the plunger continues 4o to move downward the springs 39, 40. 4l and 42 are forced into Contact with the springs 38, 37, 44 and 43, respectively. il. number of thesey line switches are mounted side by side upon a frame comprising a pair of an- -45 glo irons 5l and 52 (Fie. 5). Above these switches, and parallel with these angle irons7 there extends a rotatable shaft On the shaft 53', opposite each the individual switches, there is member 54. ber 54 is provided with a curved flange 55. In the center of this dange there is a'notch 56. @n the upper end oi the plunger of the' Solenoid 47 there is a small hat projection 57 which is adapted to normally 55 the notch 56 in the liange 55 the plungers of all the individual switches are normally locked with the shaft and, through the medium thereof.,` may be 'moved bach' and forth in front of their respective 6o banks of contact springs.

switch is operated., 'however,' its plunger passes out oi' control ci? the shaito. it. when a line switch returns from its open ated to its normal position, the shaft 53 is not standing in the same position in which Nh'enl a line it when the lin:n switch 'was operated, the projection 5'? on tl` i of the plunger of 'the line switch will not -ngage the notch but will strike somewhere on the smooth sui Lce or' the cani 55. lluring the subsequent movements ci the shaft 53 the line switch will then remain stationary, with its plunger standing" in iront of the group of contacts from which it was just disengagged, until the shaft returns to the position in which was when that particular switch was operated.' liv-Then. the shaft reaches this position, the projection 57 drops into the notch 56 and the plunger will again become locked with the shaft. The nieveinent of the shaft is controlled by a inaster switch such as, shown in Figs. Z and 8, and in a nianner to be hereinafter described.

To each of the line switches there is allotted one `of the combined line cutoff relays, as shown in Fig. l.. These ays are mounted vertically, opposite their respective switches., upon a strip 220 which is secured to the angle iron 5l (Fig. 5). rEhe relays `are secured to the strip 220 byl a screw which passes-through the hole 9.2i in the rectangular piece 222 (Figs. l, 2 and 3). A

llhe master switch shown in Figs. 7 and 8 is assembled upon a base or frame G0 which is adapted to be mounted upon the angl irons 5l and 52 (Fig. midway of their length, with an equal number of line switches on either side of it. @n the end of the shaft 53' (Figs 6 and T) there is a downwardly projecting link 6l, to the lower end of which there is secured a short shaft 62. The end or' the shaft G2 is supported by a. bearing in the stationary support G3. The line switches on the other side of the niaster switch are pro-vided with a plunger shaft similar to the-shaft 53, and which in turn is connected with a shaft 64 which similar to the shaft 62. `The shaft 34 passes through a bearing in the support For simplicity, the supports h3 and -65 are omitted in Fig. 8. The shafts 62 and 64 are irinly clalnped together by means of a divided hollow shaft 66, through which the ends of the shafts 62 and 6.4 pass and to which they are securely fastened. Firnily secured to the shaft 66 there are two arios 67 and SS, a notched cani G9 and a geared segment 70. The shaft il@ is also connected with the plunger of a solenoid 7l by means of an arni W. Adapted to register with the notches in the cam G9 there a locking dog 73 which is controlled by the armature of the relay 74 through the medium of the arm T5. rlie relay 74 also controls the Contact springs 76, 777 78 and 70. W hen 'the relay 74 is energized7 the dog '73 is disengaged from the cani 69 and the shaft G6"is then free to rotate. l?. the solenoid is not enerlifirled, the shaft will be rotated in a counter vlockwise direction by the spring S0., l/Vl solenoid is energized, ,it rotates the shaft 66 in a clockwise direction against the tension of the spring 80. In its normal operation the shaft 66 is rotated in eitherl direction only far enough to carry the last notch the cam'69 past the dog rl`he motion of the shaft 66 is transmitted to the plunger shaft and the corresponding shaft on the other' sie' i of the master ,switch to give them the cam 69 for each set of springs in the banks of the line switches, and the notches are so spaced that when the'dog 73 is in engagement with any 'one of' them, the plungers ofl the line switches that are in engagement with the plunger shaft will be in i line with the corresponding sets of springs in their banks. The arm 68 of the master switch is adapted to forcethe spring 81 into contact with the spring 82 when'the upper notch in the cam 69 reaches a position just below that in which it registers with the dog 73. The arm 67 is adapted to depress the spring 83 when the shaft 66 is rotated far enough to bring the lowest notch of the cam 69 slightly above the end oi.l the -dog 73. In order to operate the springs at the proper time, the arms 67 and 68 may be adjusted bybending, or they may be provided with adjusting screws or other well-known means of adjustment. The speed of the operation of the master switch is controlled by a governorcomprising a pair of weighted springs S4 and 85 secured to a shaft 86 which is geared to thefsegment 70. As the master switch operates, the shaft 86 rotates and causes the ends of the springs 84 and 35 to fly outward and rub on the inside of a stationary cup 37 to produce a braking action.

ln Fig. 9 there is shown a substation A to the line conductors of which there is allotted at the central oflice one of the subscribers indi vidual switches shown in Figs. 5 and 6. in these figures the line switch is represented diagra-inmatically by one of the sets of springs 37-44 and the solenoid 47. As has been explained, each line switch is provided with a number oi such sets of springs. Each oi? these sets forms the terminal of a. trunk line leading to a selector switch E. Each trunk line is connected in multiple with the corresponding set of springs in thebanks of all the lineY switches which are controlled by the same master switch. lThe subscribers line conductors are connected in' multiple with the springs 40 and 41 of all 'the sets in its own line switch. This trunking arrangement is the same as described in British'flatont No. 26,301 of`l906; l I

To each subscribers line there is also allotted one of the combined line 'and cutoff relays 6 and 5, shown in Figs. 1 to 4, inclusive. The line relay. 5 has only a single pair of contact springs 88 and89. The cutoff relay 6 has two groups of springs, each of which is represented by an armature and ra front and backcontact.

In reality each group would consist of a pair of springs, such as 24 and 26, on the upper side of the relay (F ig. 2) and another'pair of springs, such as 29 and 33, on thell'ower side. By connecting the springs 24 and 29, these two pairs of springs form the equivalent of a simple make-and-break device, as represented in Fig. 9.

At D there is'shown a master switch of tact corresponding to the trunk line before i whichvthe plungers are being held by the master switch.

The two relays 92 and 93 shown justabove the line switch C are common to the entire group of switchescontrolled by the master switch D. These rela-ys are 'slow-actingthat is, slow to denergize. rilhis slow action may be obtained by placing al ring of copper around one end of the core of the relay.

The selector switch E is-of the general type disclosed in United States Letters Patent No. 815,321, granted `March 13, 1906, to Keith, Erickson & Erickson, being modiiied somewhat, however, in order to operate in a two-wire system. As herein represented,`

the selector comprises the usual wipers 94, 95 and 96 carried upon a shaft (not shown) Vwhich has a vertical motion controlled by the vertical magnet 97 and a rotary motion controlled by the rotary magnet-98.' usual side switch comprising the wipers 99,

100, 101 and 102' is controlled by the private magnet 103 in the usual and well-known manner. The usual means of releasing the switch are provided in the release magnet 104. The springs 105 and 106 are permitted' to close only when the switch shaft is raised one or more steps from its lowest position. The relays 107 108 and 109 are slow acting relays. The shaft will' release immediately upon the energization of its release magnet,

rather than by its denergization 'as shown in the said selector patent No. 815,321. The

selector F isessentially the same as, the se lector E. l l

The connector H (Fig. 10) is ofthe general type disclosed in United States Letters Patent No. 815,176, granted March 13, 1906,

The

g l l maaar@ to Keith, lilriclso'n t Erickson, hut, like the selector, is modified to operate in a tvo-w1re system. This connector comprises the usual wipers 110, 1 l and .112 carried upon a ver y rounded at G is shown for su )olvin cur- I The relays rent for operating the switches and for talking purposes. rlhe connector ll is repre sented as having obtained connection with the line ot substation A", which line is provided with theline switch C', in all respects imilar to the line switch C (Fig.a

In order to give a clearer understanding of my invention, l will. explain in detail how the subscriber at substation A may ohtain connection with the subscriber at suhstation A', the number of which will he assumed to he #2229. Upon removing his receiver from the switch hook, the suow scriher at substation A permits the spring 116 to engage the spring 117, whereby a circuit is completed-extending from ground G through the springs 118 and 119 of the cut-o relay 5, line 121, springs 116 and 117, 122 and 123'; receiver 124,'transmitter 125, line 126, springs 12S and 127 and line winding 6 to the battery lead 130, thence through the battery B to ground The relay 6, upon energizing, completes the circuit from ground G2 through the slow'acting relay 92, springs 88 and 89 of the relay 6 and the solenoid 47 o the line switch to the battery lead. gized over this circuit, but it has a comparatively high resistance and does not permit sufficient current noid i7 to cause it to 92, upon energizing,

operate. The relay completes a circuit yfrom ground G2 through the armature 135 and its' front Contact, relay 93 and the springs 79 and Z8 to the battery lead 130. The relay 93, upon ener izing, connects the ground G5 with tre solenoid '17 direct,

The solenoid is thereupon operatively energized. 92 and 93 are slow acting and thereforel maintain the circuit of thesolenoid e7 long enough to cause it to operate, even though 'the relay 92 is shortcircuited hy the energiaation of the relay 93. rEhe solenoid el?, upon energizing, forces the plunger of the line switch into the set of bank springs betere which it is resting, 'lorc- `ing them into contact in pairs, as has been already described. rthe engagement ot' the springs 0i/and 41 with the springs 37 andl 4111, respectively, extends the' line connection to the :lrst selector E, whereupon its line All .il

. (which is assumed to he in g to the trunk line leading to the selector rlhe relay 92 isener-v "plunger shaft when it tofiow through the sole- 131 hecoines energized over a circuit G3 through side switch relay extending from ground lower winding oft' said relay, wiper 100, springs le 4:1, line 121, thence through substation and ha over the other side ot the line, through the springs 4:0 and 37', side switch wiper 99 and the upper winding olf the relay 131 to the hattery lead. he relay 131, upon energizing,

lconmletes a circuit extending from ground Gt through thel springs 132 and 133 and relay 107 to the battery lead.4v rl`he relay `107, upon energizing, completes a circuit from ground G5 through the springs and 135, 38 and 39, cut-.off relay f5 and the solenoid il?. rlfhis circuit energizes the lay G and provides a holding circuit for the solenoid 47. The relay 5, upon energizing, disconnects the line relay from the line.

lWine/n the springs s2 and 43 are forced into contact hy the plunger of 'the line switch, a circuit is closed from ground G through said springs, master switch hanlr contact 123'? the contact belongll), wiper 91, common segment and re lay' 138 to the battery lead. The relay 13S, upon energizing, completes a circuit through the relay Tel. The relay 7.4,-, upon energizing, separates the springs 79 and 78, closes the contact between the springs 77 and 76 and withdraws the locking dog- 'I3 from the cam 69. As soon as the cam is unlocked, the spring 8O (Fig. 8)'l begins torotate the master switch shaft thereby-'causing the alunger shaft 53 to move the plungers ot' all of the idle line switches which are in engage ment therewith away from the trunk line 'just seized hy the switch ,C. Ot course, the switch (l becomes operates, and is therefore not a'ected by the movement ot the plunger shait. After the plungers have heen moved a short distance, the master switch wiper 91 passes ollthe Contact 187, which allows the relay 138to-denergize and hrealf. the circuit ofthe relay 74. rlhe relay le thereupon allows the dog 73 to drop hack and engage the next notch in the cam 69,

which stops the masten switch and the plunger shaft with the plungers resting in front of the next trunk line-that is, provided this trunk line is idle. It this trunkl line is busy, however, the wiper 91 will find the next contact grounded, which will cause the relays 13S and 7l, to remain energized, while the next opening in the cam 69 is passing the dog `73, and the plungers will he carried past the busy trunk to an idle one. ,li the plungers ot the line switches aye being held in front of the last trunk and this trunk becomes seized by some line switch, or it this trunk is lousy when the pl'ungers arrivi; opposite it, the Ymaster switch will start to move the idle plungers on pasa this trunk, hut

disengaged from the after they have moved a short distance .the arm 68 forces the spring 81 into contact with the spring 82. This closes a circuit from ground G1 through the springs of the relay 138 (said relay being energized because the wiper 91 is in engagement with the guarded contact of the last trunk, which'is assumed to be busy), springs 81 and-82relay 139 and springs 76 and 77 to battery.'l The relay 139 thereupon energizes, forcing the springs 140, 141 and 142 into contact, in which position .said springs become locked by the coperation'oi the lug on the top of the spring 83 with the spring 140. The engagement of the springs 141 and 140 completes a circuit from ground G8 through the said springs and through the relay 138 to maintain the relay 138 energized regardless of the wiper 91. The engagement of thesprings 141 and 142 completes a circuit through the solenoid of the master switch. The solenoid, upon rao energizing,'rotates theI shaft 66 (Fig. 8) in Aa clockwise direction, thereby causing the plunger shaft 53 to carry the plungersof the idle line switches back to the position opposite the first trunk. When the plungers reach this position, the arm 67 depresses the spring 83, which allows the spring of the relay 139 to restoreto normal position, thereby breaking the circuit 'of the solenoidA V ..71 and the relay 138.. The relay 138, upon denergizing, allows the relay 74 to denergize, which permits the dog 73 .to drop into the cam .69 and lock the master switch with the p'lungers Standing opposite the first trunk. From the above itis evident that the master switch operates tovadvanee the plungers of the idle lin'e switches whenever any one of said switches is operated. Thus, when a switch is released from its operated position, the notch 56 (Fig. 5) .in the member 54 will have moved out of register with I the projection 57 on the end otthe plunger of the solenoid'47, and the projection 57 will come into contact with the flat projection or Flange 55. During subsequent movements of the master switch, this particular line switch will remain stationary, in front of the trunk line from which it was just disengaged, until the plunger shaft returns to the position inwhich it was restingl when this switchwas operated, whereupon the projection 57 will drop into the notch 56 and this line switch will again become locked with the plunger shaft. Tf a second call is sent in over this line switch after it has been released, and before the projection' 57 engages the notch 56, the line switch will engage the same trunk line from which it was last released.

'During the operation of the master switch it will be seen that the springs 78 and 79 of .therelay 74 are open. Thus, if any subscriber removes his l.receiver to make a call at this time, he will be unable to .close a circuit throughtlierelay 93, and therefore will .calling substation.

is to prevent the operation of the line switches while their plungers. are being moved from one trunk to another.

The foregoing'are the operations that take place upon the removal of the receiver at the The calling subscriber now operates his calling device for the digits of the number 2220. This callingv device is represented diagrammatically in the drawings by the ,impulse springs 122 and 123 and an impulse wheel 143. The impulse wheel 143 is controlled by the callin subscriber. through the medium of a dial not shown) provided'with finger holes. When the dial is operated for therst digit 2 of the'desirednumber, the impulse springs 122 and 123 are separated twice momentarily. Each time the springs'122 and 123 are separated, the energizing circuit of the line relay 131 of the selector E is broken, allowing said relay .to be momentarily denergized. Since the relay 107 of the selector is slow acting, it does not have time todenergize during the momentary interruption of its circuit at the -wiper 101 to the battery lead 130. Since the digit called is 2, the vertical magnet receives two impulses over this circuit and operates to raise the switch shaft and wipers two steps to aposition opposite the second row or level of bank contacts. The private mag-v .i

net relay 108, which is included in the energizing circuit of thevertical. magnet, is energized with the first impulse, but being a slow acting relay does not have time to deenergize until the last impulse for the digit is transmitted. In its energized condition the relay 108 operates to close a circuit eX- tending from ground G"c through the springs 148 and 149 and private magnet 103 to the battery lead 130. When the relay 108.A denergizes, after the last impulse is` transmitted to the vertical magnet, this circuit through the private magnet is broken.

The private magnet thereupon denergizes and allows the side switch to -pass to second position. The movement of the side switch wiper 101 from first to second position disconnects the battery from the vertical magnet 97 and completes an energizing circuit through the rotary magnet 98. This 'circuit extends from ground G3 through the inter'- rupter springs 150, rotary magnet 98, relay 109 and side switch wiper 101 to the battery lead 130.- Upon the closure of this circuit the rotary magnetv attracts its armature, which operates'to rotate the shaft wipers one step, to press down the armature of the prig 102,- springs 156 yate magnet 103 and open the circuit of its ouT magnet at 'the interrupter springs rl. .lnen the circuit of the rotary magnet is thus opened, its armature falls ifck and, if the first trunk line upon which the c have just been rotated is not already in use, the private magnet armature also lls baclr and permits the side switch to ss to third position. if, however, the il line of the second level is already busy, private Wiper 96 finds the. irst Contact .eh it engages provi-ded' with a guarding und potential. lll/711erl the Wiper 36 thus the grounded contact, a locking circuit is completed through the side sw'ftcn xer te magnet 193 to battery lead 130. rEhe ,vate magnet thus becomes energized and Pla locks the side switch 1n second position. i

long as the side switch remains thus locked, the rotary magnet continues to operate in a nanner similar to that of a buzzer to rotate the selector Wipers step by step until an idle trunk line 1s found. ltr/Then the privateA Wiper 96 engages the noirgrounded Contact of an idle trunk, the private magnet 103 deenergizes and permits the side switch to pass to third position, thereby breaking the circuit ofthe rotary magnet. Il" he movement of the side switch wipers 99 and 10G from second to third position disconnects the line relay 1231 .from the line and extends the line connection through the shaft Wipers and 95 to the second selector l?. Vlhe line relay 151 in the selector l? then becomes energized in the same manner in which the relay 131 of the selector lli was energized when the connection was first extended to that selector. l

rlhe-energizaticui of the relay 151 serves to close an energizing circuit through the slou7 acting relay 152 in the same manner in which the circuit of the relay 107 of the selector E was closed by the relay 131. The relay 152, upon energizing, extends a gua-rdf' ing potential from ground G10 through the side switch Wiper 158 and springs 1r and 155 to the private bank Vcontacts of 'the seized trunk in theV banlrs oi all oi' the selectors E which have access to 'this trunk. r

'circuitalso extends ro'ni the ground G10 through the said selector private banlr con tects, private Wiper 9o, side switch Wiper and 157 and relay 10im to the battery lead 130. rllliis circuit prevents the relay 107 from deenergizing after its former circuitis broken by thedeenergizai tion of the 4relay 131 when the side switch of the selector E passes to third position. A

short period 'oit time elapses between the time when the side switch. of the selector E passes to third position. and the time when the relay 152energizes to extend a guarding potential. baci; to the first selector private bank contacts from the ground G10. @urine i 102 (in second position) and the pri-v manner that the selector line relays are envgizing, extends theguarding poteni .groun d this interni the trunk line leading to the selector i?" is guarded by a g v@und potential errtendino` from ground G11 through the springs 15S and 106, side switch Wiper 102 and private wiper El@ to the private bank contacts. lt will be remembered that the relay 109 is included in tlieoperatrog cir-- cuit of the rotary magnet 98 and, since it is a slou7 acting relay, it remains energized 'for impulses for this digit in theamemanner as explained for the selector E, and extends connection to an idle connector E over the trunk lines 159 and 160. lllhen the connectien'is thus extended to the connector H, its line relay 162 becomes en ized in the same orgineel. The relay162, upon energi operates to complete ay circuit extend from groimd G12 through the springs and 161- and the slow acting relay 1F36 to the battcrylead 130. The relay 166, upon G13 through the side switch y A, l 1G?, spri es 168 and 169 andconductor lol. to all of ythe selector private bank. contacts which belong to thetrunlr line leading to the connector H. The energization of the relay 166 of the connector also provides a new holding circuit for the release relays 152 and 1G?Y of the selectors F and E, rcspectvely.

The calling subscriber now operates his dial for the third digit 2, momentarily separating the substation impulse springs 122 and 123v in the saine manner' as described for the first digit. springs are separated 'for the third digit, the energizing circuit for the connector line relay 162 is broken momentarily. Since the relay 16 et' the connector is slou7 acting it does not have time to denergize during the momentary deenergizati'ons of the relay 162. Consequently, the engagement of the springs 163 and 165 completes an energizing circuit through the vertical magnet 113. This circuit extends .from ground G12 through the springs 163 and 165, springs 170 and 172,

lafch time the impulse tory lead'lBO. The Vertical magnet receives two impulses over this circuit and operates to raise the shaft wipers 110, 111y and 112 MMM..

operates in the same manner as the private magnet relay 108 of the selector E to close `ceive impulses for .the last digit 0.

the circuit of the private magnet 115 while the vertical magnet is operating. The cir cuit through the private ,magnet extends from gro' nd G14 through the springs 176 and 178 i nd private magnet 115 to the battery lead 130. This circuit is broken shortly after the last impulse is delivered to the vertical magnet, whereupon the private magnet denergizes and permits the side switch to pass to second position. The movement' of the side switch wiper 1.74 from first to second position transfers the battery connection from the vertical magnet 118 to the` rotary magnet 114. The connector is then'in position to re- The operation of the substation calling device for this digitv breaks theenergizing circuit of theA relay 162` ten times. Each Y time the relay 162` denergizes it \completes a. circuit extending from ground G12 through the springsl 163, 1,65, 170 and 172, springsV 180 and 181, rotary magnet 114, side switch wiper 174 (in second position) and lrelay 17 5 to the battery lead'130. The rotary magnet 114 receives ten'inipulses over this circuit and operates to rotate the wipers ten steps onto the contacts of the li-neNo. 2220. The

private magnet relay 175 is energized by the first impulse to the rotary magnet and again closes the circuit of the private magnet 115,.

The circuit of the relay 17 5 is not opened.

longenough to permit it to denergize until after the last impulse has been delivered to the rotary magnet.. The relay 175 thendeenergizes and breaks the vcircuit of the private magnet 115 which, it the called line is not already busy, in turn denergizes and a guarding potential from ground G1 permits the side switch to pass to third position, whereby connection is completed be tween the calling and called lines. The side switch wiper 183 (in third position) extends through the private wiper 112 to the` con nector private bank contacts of the called line, and also provides an energizing, circuit for the cut-oil' relay 184 of the line switch C. The'energizing circuit of the relay 184 also includes the solenoid 185, but the resistance of the relay 184 is high enough to prevent suiiicient current from flowing to operate the solenoid.' Jlklthough this current is not strong enough to operate the line switch, it is suilicient to hold it in its operated position, as explainedin connection with the line switch C of the calling line. The relay 184, upon energizing, cuts oli the line rela-y 186 and connects the called line with its connector 'bank contacts. Then the side switch'wiper 174 of the connector reaches third position, the energize ing circuit is established .for the ringer relay 187. This circuit extends from ground G17' through` the interrupts-.r 188, springs 189 and 190, relay 187, side switch wiper 174 and relay 175 to the battery lead'130, Since this circuit includes the interrupter 188, the

relay 187 is energized only intermittently. v

Each time the relay 187 is energized it'opcrates to disconnect the calling line from 197 and 198, 'substation impulse springs, 11e-I ceiver'and transmitter, line 199, shaft Wiper '110, side switch wiper 200, ringer relay springs 201 and 202, upper Winding of the back bridge relay 192 to the battery'lead 130. vWhen the connector back bridge relay 162 is energized, it breaks the circuit""of the ringer relay 4187 at,the springs 189 and 190 to preventvfurther application of ringing current to the called line.,

After the conversation is mnipleted, the release of the` central o'llice apparatus is initiated by the hanging up of the receiver aft the calling substation. When the receiver 124 is restored to the switch hook, 'the springs. 116 and 117 are separated, thereby breaking the energizing circuit'through the connector line relay 162. The relay 162, upon ,denergizing breaks the holdin cuits `olt the release relays 166, 152 and 107 soA ot' the switches 11, F and E, respectively.

It will. be seen that when the side switch wiper 16T of the connector passed. from second to third position, the holding ground of the release relays 152 and 107 o1" the selector switches was transferred from ground G13 to ground G12 through the springs 164 and 163, so' that the circuits of all of the release relays are controlled at this time by the connector line relay. Villien the relay 16,6 of the connector ydenergizes.

it completes a circuit from ground G12 through the springs 163 and 165., springs and 171-release magnet 203\and oli `normal springs 204 and 205 to the battery lead 130. The energization ot' the magnet 203 immediately restores the mechanism of the connector .to normal position, thereby breaking the connection with 'the called line l and allowing the relay 184 of the called line to denergize. The denerg-ization vof the release relays 107 vand 152,01? the selectors E and'F closes the circuits oftheir respective release, magnets. The energizing cir- -the release magnet 20G 01"' the selector F is similar' tothat just traced for the niagnet 104. rThe energization of the magnets. 10i and 20G restores the mechanism of their respective switches to normal position. When the shafts of the switches E, F and H reach their lowest positions, the. ener-A gizing circuits ot' their respective release magnets are broken by the separation of thc oil' normal springs. The denergization of the release relay 107 of the selector E also opens the holding' circuit of the-relay 5 and solenoid 1&7 in the line switch C, whereuponv its plunger returns to normal position andi all ot the apparatus employed in the connection is vleft in readiness for another call.

The foregoing is an explanation of how' connection is completed 'with an idle line. lt will now be explained how the calling subscriber'is given a busy signal in case the called line is in use. lt has been eX- piained how the connector 'private bank contacts of the called line are provided with a guarding potential. lt will be evident that the calling line is also provided with a guarding potential extending 'from ground G5 at the selector E, through the springs 134 and 135, springs 38 and 39 and conductor 290, which leads to the connector private bank contacts of the substation A.

Thus, whenever' the private wiper 112 of the connecten engages the co'ntact of a busy line, a. ground potential .is extended from the grounded private bank contact of said line through said wiper, springs 209 and 210, lowerwinding of the relay 192,"springs' 193 and 194 and side switch wiper 195 (in second position) to the spring' 177 of the private magnet relay 175. l Thus,-when the relay 175 denergizeslafter the last digit is called, the circuit of the private magnet is not opened, .but is shifted from ground G14 to the ground'lat the private wiper by the, engagement of the springs 177 and 178. The. relay 192 thereupon becomes energized, because its lower winding is included in the holding circuit of the private magnet, and a circuit is closed from ground G1* through the springs 176 and 179 of the relay 175, springs 212 and 211, relay 213 and springs 211i to battery. The relay 213, upon energizin'g, shifts the holding circuit 'of the private magnet and relay 192 from the 'private wiper to ground G20. Since the orl- I vate magnet does notdenergize, the side switch remains locked in second position without completing connection with the' busy line and `Vthe busy signaling machine `M is connected with the calling line through nisaeio the springs 215, side switch wiper 200 Qin .second position), springs 201 and 202 condenser 216.

` l/Vhile l have shown my invention in connection with a full automatic` system in which iirst and second selectors and connector's employed, it will he read-ily understood that my improved form of line'and masterswitch is equally as well adapted for use in a semi-automatic systemthat'? motion.

2. ln a telephone syst-ein, a group of trunk lines, a plurality of line switches for selecting idle trunks, a master switch for controlling a group ot said line switches, and a spring in which energy is stored up for supplying the entire operating-power for said master switch. l

3, ln a telephone system, a group of trunk lines, a plurality of line switches for selecting idletrunks, a'inaStersWitchfOr controlling a group of saidn line switches', means :for operating said. master switch, and a solenoid-for restoring said switch and operat- .ing means 'to operative position.

4C. lin a teleplmne system, a group of trunk lines, a plurality of lineswi-tches for selecting idle trunksfa master switch for controlling a group of said line switches, a solenoid magnet, a spring, said master switch having a continuous selecting motion 'controlled by said spring, and a non-selecting return motion controlled by means or" said solenoid magnet. v

5. 1n a telephone system, a group of trunk lines, a plurality of line switches for selecting idle trunks, amaster switch for controlling a group of said line switches,

spring under tension for operating said master switch, a cam provided with a series of notches, a dog adapted to Aengage with said notches normally preventing operation oi said master switch, and means for releasing said dog to permit the operation 'of said master switch.' o

G. ln a telephone system, ay subscribers line, a'plurality of trunk lines extending" therefrom, a line` switch for connecting with i an idle trunk, an operating magnet 'for said switch, and means 'for moving said magnet inthe operation of said switch. 7. ln a telephone system, a subscribers line,l a plurality otftrunk lines eXtendin .therefrom'a line switch for connecting with plunger, said plunger. being connected directly to the core of said solenoid.

9. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting With an idle trunk, a pivoted operating plunger for said switch, andan operating magnet the core of Which is connected directly to said plunger.

10.- In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with idle trunk, a plurality of sets of normally separated contacts, an operating plunger adapted to engage With any one of said sets, ,and an operating magnet, said plunger being con nected directly to the armature of said magnet, said magnet being pivoted and adapted to rotate in thev selecting operation of said switch.

11, In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch having a plunger for connecting With an idle trunk, and an operating magnet for said switch provided with an operating winding, said switch adapted to be maintained in its operated position by the continued energization of said operating Winding.

12. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch having a plunger for connecting with an idle trunk, a line relay permanently connected to battery, an operating magnet controlled by said relay, an operating Winding therefor, and means for maintaining said switch in operative position by the continued energization of Said operating Winding.

18. In a telephone system, a subscribers line, a plurality of trunk lines extending v therefrom, a line switch for connecting with feo an idle trunk, an operating magnet therefor, a high resistance relay adapted to be included in circuit with said operating magnet, and means for short-circuiting said relay to permit the operation of said magnet.

1t. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with an idle trunk, an. operating magnet therefor, a slow acting relay adapted to be connected in circuit with said operating magnet, a

second relay controlled by said first-mentioned relay, and means controlled by 4said Vsecond relay for short-circuiting said firstmentioned relay to thereby permit the oper* ation of said operating magnet,

15. In a telephone system, a plurality of subscribers lines, aplurality of trunk lines extending therefrom, a line switch allotted to each of said subscribers ylines for selecting an idle trunk line, a master switch for controlling a group of said'line switches, an operating magnet including an operating Winding for operating said line switch, said switch being adapted to be maintained in operative position through the continued energization of said operatingwinding, and means for' rendering an idle line switch inoperative While its master switch is operu ating. 16. In a telephone system, a plurality of subscribers lines, a plurality of trunk lines extending therefrom, a line switch allotted an operating magnet for said line switch controlled by said line relay, means whereby said switch is maintained in operative position through the continued energization of said operating magnet, and means for reir dering an idle line switch inoperative While its master switch is operating.`

17. In a telephone system, a plurality of subscribers lines, a plurality of trunk lines extending therefrom, a line switch allotted to each of said subscribers lines for selectingan i'dle trunk line, a master switch for controlling a group of said line switches, an operating magnet therefor, a relay adapted to be included in the circuit of said operating magnet to prevent the operation there of', a second relay adapted to short-circuit said first-mentioned relay to permit the operation of said operating magnet, and means for opening the circuit of said second' relay when the master switch is in operation.

18. In a telephone system, a subscribers line, a line switcli'therefor, a solenoid*mag-A net lcontrolling the operation of said line switch, a line relay for controlling said solenoid magnet, and a cut-olf relay adapted to be. energized to cut off said line relay from the line, vsaid cut-off relay and line relay being combined in a single unitary structure. 19, In a telephone system, a plurality of' subscribers lines. trunk lines, a line switch for each subscribers line for connecting with idle trunks, means for controlling said line switch over two sides of the s1il.)scribei"s line in series, and a. master switch for controlling a group of said line switches, said master switch having a continuous selecting motion and a continuous non-selecting returnl motion. Y

20. In a telephone system, a line circuit a group of trunk lines, a plurality'of line switches for selecting idle trunks, means for controlling said line switches over two sides of the line circuit in series, a master switch for controlling a group of said line switches, and a spring in which energy is stored up for supplying the entire operating power for said master switch. 2l. In a telephone system, a line circuit,

a group of trunk lines, a plurality of lineA switches for selecting idle trunks, means for controlling said line switches over two sides of the -line circuit in series, a master switch for controlling a group of said line switches, a solenoid magnet, and means to control said vmaster switch through the medium of said magnet.

22. In a telephone system, a line circuit, a group of trunk lines, a plurality of line switches for selecting idle trunks, means for controlling said line switches over two sides of the line circuit in series, a master switch for controlling a group of said line switches, means for operating said master switch, and a 'solenoid for restoring said switch and operating means lto operative position.

23. In a telephone system a line circuit, a group of trunk lines, a plurality of .line switches for selecting idle trunks, means for controlling said line switches over two sides of the line circuit in series, a master switch for controlling a group of said line switches, and a solenoid magnet, said master switch having a continuous selecting motion controlled by a spring, and a non-selecting return motion controlled by means" of said solenoid magnet.

24. In a telephone system, a line circuit, a group of trunk lines, a plurality of line switches for selecting idle trunks, means for controlling said line switches over two sidesy of the line circuit in series, a master switch for controlling a group of said line switches,

'a spring under tension for operating said master-switch, a cam provided with a series of notches, a dog adapted to engage with said notches normally preventing operation of said master switch, and means for releasmg said dog to permit the operation of said master switch.

25. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with an idle trunk, an operating magnet for said switch, means for moving said magnet in the operation of said switch, and means for controlling said magnet over two sides of the line circuit in series.

26. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with an idle trunk, a solenoid magnet for controlling the operationof said switch, the said magnet adapted to ,be moved during such operation, and means for controlling Asaid magnet over two sides of the line circuit in series. 1

27. In a telephone system, a subscribers line, a plurality of trunk linesextending therefrom, a line switch forconnecting with :an idle trunk, said switch including a plurality of sets of contacts, an operating plunger adapted to engage any one of said sets of contacts, a solenoid for operating said plunger, said plunger being connected directly to the core ofsaid solenoid, and means for controlling said switch over two sides of the line circuit in series.

28.'In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with an idle trunk, a pivoted operating plunger for said switch, an operating magnet the core of which is connected directly to said plunger, and means for controlling said switch over two sides of the line circuit in series.

2.9. In a telephone system, a subscribers line, a plurality'oftrunk lines extending therefrom, a line switch for connecting with an idle trunk, aplurality of sets of normally separated contacts, an operating plunger adapted to engage with any one of said sets, an operating magnet, said plunger being connected directly to the armature of said magnet, said magnet being pivoted and adapted to rotate in the selecting operation of said switch, and means for controlling said switch over' two sides of the line circuit in series.

30. In a telephone system, a subscribers line, a plurality of trunklines extending therefrom, a line switch for connecting with an idle trunk, an operating magnet for said switch provided with an operating winding, said switch adapted to be maintained in its operated position by the continued energization `of said operating winding, and means for controlling said switch over two sides of the line circuit in series.

31. In a telephone system, a subscribers line, a pluralityv of trunk lines extending therefrom, a line switch for connecting with an idle trunk, a line relay permanently connected to battery, an operating magnet controlled by said relay, an operating winding therefor, means for maintaining said switch in operative position by the continued energization of said operating winding, and

means for controlling said switch over two sides of the line circuit in series.

32. In a telephone system, a subscribers line, a plurality of trunk lines extending therefrom, a line switch for connecting with rn idle trunk, an operating magnet therefor, a high resistance relay adapted to be included in circuit with said operating magnet, means for short-circuiting ysaid relay to permit the operation of said magnet, and means for controlling said switch over two sides of the line circuit in series: l

33.- In a, telephone system, a shulrserbers line,u a'plurality of trunk 1in`es"'*extending therefrom, a line' switch for connecting with v an idle trunk, an operatingvmagnet therefor, a slow acting relay adapted to be connected in circuit With said operating magnet, a second relay controlled by said rst-mentoned relay, means controlled by said relay for short-circuiting said first-mentioned relay to thereby'permit the operation of said operating magnet, and means for controlling said switch over two sides of the line circuit 15

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